A 2012 inquest into Ms Pickett's death found WA police failed to investigate or act on multiple breaches of violence restraining orders by Pickett.

Today in Perth's District Court her family filed a statement of claim, seeking financial compensation and systemic changes.

Ms Pickett's brother Gary Bentley says the WA Government and police failed in their duty of care to protect her.

"I believe Andrea would still be alive today if the systems that are in place were just followed through, or investigations done, then it could be a whole different thing today than it currently is," Mr Bentley said.

She was killed in an horrific way on the police's watch and on the West Australian Government's watch.

Andrea Pickett's brother Gary Bentley

"We're trying to achieve accountability for the multiple times that police failed Andrea.

"She was killed in an horrific way on the police's watch and on the West Australian Government's watch.

"Her killing was preventable and the police need to understand they had a duty of care."

Western Australia's Attorney-General Michael Mischin says it is not appropriate to comment on a case that is before the courts, a statement echoed by West Australian Police.

Andrea Pickett went to police four days before her death

Ms Pickett was stabbed to death at a North Beach house in January 2009.

One of her young daughters was in the home at the time and witnessed her mother being murdered.

Her husband was on parole at the time and was also the subject of a violence restraining order taken out by Ms Pickett.

The 39-year-old went to the Armadale police station just four days before her murder. She reported a breach of the violence restraining order after discovering handwritten letters from Pickett and a machete at her home in Brookdale.

The day before her death Ms Pickett was told by Crisis Care, a Government department for child protection and family support, they could not provide any safe accommodation for her and seven of her children.

On January 12, 2009, Pickett broke into Ms Pickett's cousin's house, where she was seeking refuge.

He stabbed Ms Pickett 17 times, leaving her to die in the street at the front of the house.

It took police more than four hours to locate Ms Pickett's young daughter, who was hiding in the house.

Pickett was convicted of murder and is serving a life term in prison with a minimum non-parole period of 20 years.

A coronial inquest into Ms Pickett's death found West Australian Police failed to investigate or act on multiple breaches of violence restraining orders by Pickett.

State coroner Alastair Hope found the case file had not been allocated to any officers for investigation.

Family says there's been a failure in duty of care

Mr Bentley says despite the coroner's findings in 2012 not enough has been done.

"What we hope with the legal action is that it'll bring about that change to make people more responsible," Mr Bentley said.

"I don't know of many jobs where if you don't do your job that you'll still have a job.

I believe once an individual, a victim, has picked up their phone, the person at the other end has a duty of care to do everything in their power to help that person.

Gary Bentley

"I believe once an individual, a victim, has picked up their phone, the person at the other end has a duty of care to do everything in their power to help that person and if they don't follow through on that then the result could end up as it has in Andrea's case."

Western Australia's Women's Council for Domestic and Family Violence chief executive Angela Hartwig agrees not enough is being done to put policy into practice on the ground.